The two step selection process requires a ura3 transformation host (this host can be created using pJL164 (ATCC 87471)). After transformation with the EcoRI/BglII digested plasmid, URA3 integrants are selected on ura- plates.

The deletion strain is then recovered by selection on 5-FOA plates (loss of URA3 marker by a homologous recombination event between the two hisG repeats).

E. coli containing this plasmid should be grown on media lacking pyrimidines to select for URA3-containing cells.

This deleter vector is used to create yeast strains with a trp1 auxotrophic marker deletion.